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Surpressions de fluide et décollements. Modélisations analogique et numérique

Abstract : Overpressures of fluid are very often called upon to explain the very weak frictions observed at the base of the overlapping tablecloths or the slips of sediments on very weak slopes. Analogical modeling had however never taken them into account. In this thesis, we develop a new technique which consists in injecting air in sand models in order to simulate these overpressures. Thanks to this method, we show how the fluids act on the deformation by the intermédiaire of the forces of current (gradient of pressure), by modifying l intensity and l orientation of the effective constraints. We carry out then experiments of compressive deformation, in which we generate levels of separation while exploiting the permeability of the sand used in the construction of the models. The efficacity of these separations depends then on the pressure of fluid applied and controls the style of the deformation. These analogical experiments are compared with a digital model of distinct elements coupled to a liquid phase, which we also developed during this thesis. The confrontation of the results resulting from the two methods appears rather convincing. We simulate then gravitating slips and show how overpressures of fluid can create listric normal faults by modifying the orientation of the constraints. These experiments are finally applied to the deformations of the delta of the Amazone. The correlation between the form of the slips, the distribution of the pressures and the presence d'une bed rock in probable generation of gas, enables us to specify the origine of overpressures in this delta. To finish, we place ourselves at the scale of the sand grain, and we use the numerical method to characterize the evolution of texture d'un granular medium subjected to a gradient of pressure of increasing fluid.
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https://tel.archives-ouvertes.fr/tel-00007479
Contributor : Nathalie Pothier <>
Submitted on : Monday, November 22, 2004 - 3:16:21 PM
Last modification on : Thursday, January 14, 2021 - 11:39:50 AM
Long-term archiving on: : Thursday, September 13, 2012 - 1:10:18 PM

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  • HAL Id : tel-00007479, version 1

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Regis Mourgues. Surpressions de fluide et décollements. Modélisations analogique et numérique. Tectonique. Université Rennes 1, 2003. Français. ⟨tel-00007479⟩

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